Gear pump with thrust plate adapted to both directions of flow



Jan. 16, 1968 R. H. BOLSTER 3,363,579

GEAR PUMP WITH THRUST PLATE ADAPTED TO BOTH DIRECTIONS OF FLOW 4 Sheets-Sheet 1 Filed Dec. 21, 1966 INVENTOR RONALD H. BOLSTER Jan. 16, 1968 R. H. BOLSTER GEAR PUMP WITH THRUST PLATE ADAPTED TO BOTH DIRECTIONS 0F FLOW 4 Sheets-Sheet 2 Filed Dec. 21, 1966 FIG. 2

H @T a T5 N W B W A D M M W R f Jan. 16, 1968 R. H. BOLSTER 3,363,579

GEAR PUMP WITH THRUST PLATE ADAPTED T0 BOTH DIRECTIONS OF FLOW Filed Dec. 21, 1966 4 Sheets-Sheet 3 INVENTOR RONALD H. BOLSTER ATTORNEY Jan. 16, 1968 R. H. BOLSTER 3,363,579

GEAR PUMP WITH THRUST PLATE ADAPTED TO BOTH DIRECTIONS 0F FLOW Filed Dec. 21, 1966 4 Sheets-Sheet 4.

FIG.5

INVENTOR RONALD H. BOLSTER ATTORNEY United States Patent 3,363,579 GEAR PUMP WlTH THRUST PLATE ADAPTED T0 BOTH DIRECTlONS 0F FLQW Ronald H. Bolster, Cassopoiis, Mich, assignor to (Zlark Equipment Company, a corporation of Michigan Filed Dec. 21, 1966, Ser. No. 603,470 10 Claims. (81. 163-126) ABSTRACT OF Trill DISCLGSURE Gear pump having thrust plate for sealing the gears, utilizing pressure of the pumped liquid, having compound structure adaptable to both directions of flow.

Cross references Certain features of the present disclosure are claimed in the co-pending application of Sisson and Shreve, Ser. No. 603,467, filed Dec. 21, 1966, assigned to the assignee of the present invention.

Disclosure The present invention resides in the general field of thrust plate means for sealing the gears of a gear pump. The present thrust plate is arranged for utilizing the pressure in the outlet side of the pump and applying it against the gears in axial direction, and in such arrangement the pressure of the thrust plate is applied only against a portion of the gears, namely, that portion adjacent the outlet side and extending over a portion of the distance to the inlet side. Consequently, such a thrust plate in simple form would not be effective in pumping the liquid in the opposite direction, with correspondingly limited effectiveness and practicality of such thrust plate.

A broad object of the present invention is to provide a novel thrust plate operative for sealing the gears in the manner stated, in either direction of operation of the pump, i.e., in either direction of flow of the liquid.

A more specific object is to provide novel thrust plate means of the character stated incorporating a pair of stacked thrust plate members, respectively oriented according to the opposite directions of flow of the liquid through the pump.

A still more specific object is to provide thrust plate means of the character stated, in which the individual thrust plate members are of bellows construction placed in stacked or laminated form and expandable in response to the pressure of the pumped liquid in the corresponding directions, and wherein only one of the members is activated in any given pump operation; i.e., that member associated with the outlet of the pump according to which direction the liquid is being pumped.

An additional object is to provide a thrust plate construction of the foregoing character incorporating the pair of bellows members and a wear plate, of effective and simple mechanical construction.

Other objects and advantages of the invention will appear from the following detail description taken in conjunction with the accompanying drawings wherein:

FIGURE 1 is a sectional view through a gear pump incorporating the thrust plate of the present invention, the plane of the section including the axes of the two gears;

FIGURE 2 is an end view from the left of FIGURE 1, with the adjacent housing cover removed and exposing the thrust plate to view, the thrust plate means being viewed as oriented according to line 22 of FIGURE 1;

FIGURE 3 is a face view of the thrust plate from the opposite side of that shown in FIGURE 2, and oriented according to line 33 of FIGURE 1;

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FIGURE 4 is a large scale sectional view taken at line 4-4 of FIGURE 3; and

FIGURE 5 is an exploded view of the members making up the thrust plate, a portion of each of the bellows members being broken away.

Referring in detail to the drawings, FIGURE 1 shows a gear pump indicated as a whole at 10 including a housing 12 made up of a central housing member 14, a rear cover assembly 16 and a front cover assembly 18. The pump includes a driving gear 20 and a driven gear 22, the housing having chambers 24 and 26 receiving the respective gears. The driving gear 20 includes shaft elements 26 and 28, which may be integral with the gear, journalled in the respective cover assemblies in suitable bearings 30 and 32. The driving gear 20 also has an end extension 34 serving as a driving element which may be connected with a suitable source of power (not shown). The driven gear 22 is similarly provided with shaft extensions 36 and 38 which also may be integral with the gear, journalled in suitable bearings 40 and 42. Suitable gaskets 44 may be utilized for sealing the parts of the housing while other sealing means 46 seals the shaft extension 34 with the housing. The gears can be driven in either direction, as indicated by the double-headed arrows 47 and 48, for effecting pumping of the liquid in opposite directions, as will be referred to again hereinbelow. I

A fixed or rear thrust plate 49 of any suitable construction is utilized between the gears and the rear housing assembly, engaging the inner face 50 of the latter, and sealing the gears atthat end.

Interposed between the gears and the front housing assembly 18 is a novel thrust plate, or thrust plate means or structure or assembly 52 of the present invention and described in detail immediately following. This thrust plate includes a wear plate 54 and a pair of bellows members 55 and 56, all of congruent outline shape and so shaped and dimensioned preferably as to extend beyond the gear chambers in their greatest dimension and be gripped between the central housing member 14 and front cover assembly 18. Referring to FIGURE 1, the thrust plate is gripped between the front face 57 of the central housing member 14 and the inner face 58 of the front housing assembly, the latter formed in a recess 59. The wear plate 54 may be of suitable construction, e.g., of steel-backed bronze and includes apertures 60 for receiving the gear shafts and other smaller apertures 62 and 64 referred to again hereinbelow.

The bellows members 55 and 56 are essentially identical in construction, but with minor differences as explained hereinbelow, and arranged in opposite attitudes. These bellows members may be made substantially identical to that shown in the Sisson & Shreve application mentioned above, which broadly claims the construction. Referring to the bellows member 55 it includes a pair of plates 66 and 68 fitted together in face-to-face relation and secured together, as by electron beam welding, along a continuous line 70 outlining and surrounding a pressure cavity 72 adapted to receive pressurized liquid from the outlet passage of the pump. This pressure cavity 72 extends throughout an area which, when the member is in the pump, overlies the area of positive pressure in the pump. The upper plate element 66 is provided with an aperture 74 surrounded by a sleeve or flange 76 secured to the plate element for securing the members of the thrust plate construction together as referred to again hereinbelow. The bellows member is also provided with another small aperture 78 through both of the plate elements, and located in an area 79 in which there is no positive pressure. The area 79 is also defined by the weld line 70 which, in the assembled pump, overlies that portion of the gear chambers in which there is no pressure,

or negative pressure, at the intake side of the pump. In this area the plate elements need not be secured together. The member 55 is also provided with apertures 77 for receiving the gear shaft elements.

The bellows member 56 includes plate elements 89 and 81 welded together along a continuous line 82 defining a pressure cavity 83 similar in size and shape to the pressure cavity '72. The upper plate element 80 is provided with a small aperture 84 communicating with the pressure cavity and surrounded by a sleeve or flange 86 se cured to that plate element. The member 56 is also provided with apertures 88 for receiving the gear shaft elements.

The three members 54, 55 and -6 are stacked together as shown in FIGURES 3 and 4, with the pressure cavities 72 and 82 arranged in opposite attitudes as will be referred to again hercinbelow. In the assembly, the flange 76 in the upper or inner bellows member extends into the aperture 62 in the wear plate and is crimped as shown at 90 over a flange 92 of the wear plate formed by a counterbore in the aperture 62. The flange 86 in the lower or outer bellows member extends through the small aperture 78 in the upper bellows member and into the aperture 64 where it is crimped at 94 over a flange 96 formed by a counterbore in the aperture 64.

The pump is provided with opposed passages 98 and communicating with the gear chambers 24 and 26 at opposite sides of the pump and each forming both an inlet and an outlet passage in respectively opposite directions of rotation of the gears, the directions of flow of the liquid being indicated by the double-headed arrows 102 and 104.

As is known by those skilled in the art, the positive pressure of the liquid at the outlet side of the pump is transmitted through the gear chambers a substantial distance toward the inlet passage. Assuming a first direction of operation in which the liquid is pumped from right to left, (FIGURE 2), the positive pressure is built up in the passage 100 which is then the outlet passage, and transmitted successively through the gear teeth pockets 106, this pressure decreasing progressively from pocket 106a to 10Gb to 106C, etc., and in the example assumed, this pressure extends to substantially the region of the element 70a (FIGURE 2) of the weld line, beyond which the pressure is neutral or negative. In this direction of operation of the pump, the corresponding one of the bellows members is active, in this instance the member 55. It will be understood that the apertures 62, 74 communicate with the passage 100 and the pressure of the pumped liquid is transmitted into the corresponding pressure cavity 72.

When the pump is operated in the opposite direction, i.e., the liquid flows to the right (FIGURE 2) the passage 98 becomes the outlet passage and the pressure of the liquid there is transmitted through the gear teeth pockets and becomes progressively less in the pockets 1061, 106; 106x, etc., and is dissipated in the region of the weld element 82a which is the limit of the pressure cavity 83 in the corresponding bellows member 56. In this case also the apertures 64, 84 communicate directly with the outlet passage 98 and the pressure of the liquid is transmitted into the pressure cavity 83.

Each of the bellows members functions in the corresponding direction of flow of the liquid through the pump and neither interferes with the functioning of the other. In the expansion of the elements of the upper or inner bellows members 55 (FIGURE 4) for example, it works against the lower or outer bellows member 56, and acting therethrough, against the face 58 (FIGURE 1) of the front housing assembly 18. In that direction of operation of the pump, the other bellows member 58 is not subjected to pressure of liquid therein and of course collapses under the action of the other bellows member 55. A similar action occurs in the opposite direction of flow of the liquid, i.e., the outer or lower bellows member 56 (FIGURE 4) reacts directly against the surface 58, and against the other bellows member 55 and through the latter against wear plate 54. The plate elements on the opposite sides of the pressure cavity collapse on the intake side of the pump both by the action of the expansion of the other bellows member and by the reduction of pressure in the inlet passage.

A compound thrust plate is thus provided, one component being active in a corresponding direction of operation of the pump, while the other is inactive. The elements of the bellows members are normally sprung out and produce a pie-loading action on the wear plate.

While I have disclosed herein a preferred form of the invention, it will be understood that changes may be made therein within the spirit and scope of the appended claims.

I claim:

1. For use in a gear pump including a housing and reversibly operating gears therein, the housing defining passages that become reversibly inlet and outlet passages respectively according to the direction of flow of fluid through the pump, the pump developing pressure in the housing from a maximum at the outlet passage progressing to a minimum at the inlet passage, in each direction of operation of the pump, the construction comprising unitary and self-contained thrust plate means for positioning between the gears and an opposed surface of the housing, the thrust plate means having a pair of internal pressure cavities completely defined thereby and completely contained therein except for communicating ports, the pressure cavities being generally on opposite sides of the thrust plate means, relatively displaced in the direction between the passages, and each pressure cavity being a single suc-h cavity and extending from its associated side a substantial distance toward the other side with said port communicating with the respective passage.

2. The invention set out in claim 1 wherein each pressure cavity extends more than half the distance to the other side.

3. The invention set out in claim 1 wherein said ports are in constant communication with the respective passages.

4. The invention set out in claim 1 wherein the pressure cavities are defined by members arranged in stacked relation, and each member reacts to the pressure developed in the pressure cavity in the other member.

5. The invention set out in claim 4 wherein said members are substantially congruent and each is in the form of a bellows member made up of a pair of flexible plates secured together along a continuous line around the pressure cavity therein.

6. The invention set out in claim 5 and including means continuing the port in the member remote from the gears through the member near the gears in a portion of the latter member removed from the pressure cavity area therein.

7. The invention set out in claim 6 wherein the thrust plate means also includes a wear plate substantially congruent with said members and stacked together therewith, and positioned between the members on one side and the gears on the other side, and engaging the gears, said port continuing means also being operative for continuing the port through the wear plate, and the thrust plate means also including means for continuing the port in the member near the gears through the wear plate.

8. The invention set out in claim 1 in conjunction with the gear pump.

9. A thrust plate construction of the character disclosed comprising a pair of thrust members and a wear plate, all substantially congruent and arranged in a stack, each thrust member defining an internal pressure cavity and the pressure cavities being relatively displaced laterally, and the construction including means forming passages from the respective pressure cavities through the wear plate.

10. A thrust plate construction including a wear plate and a pair of expandable members stacked together in face-to-face relation, the expandable members having internal pressure cavities for receiving liquid therein and being expandable in the direction of stacking pursuant to the liquid being forced into the pressure cavities, and the structure forming a passage communicating with each of the pressure cavities and leading through the Wear plate to the opposite side of the Wear plate from the expandable members.

References Cited UNITED STATES PATENTS 2,714,856 8/1955 Kane 103-126 Aspelin 103126 Oliver 10-3126 Thrap et a1. 10312 6 Lockett 103-126 Clark et a1. 103-126 Gordon 103126 Sisson et a1. 103-426 Kita 103-126 Clark et a1. 103126 DONLEY I. STOCKING, Primary Examiner. W'ILBUR J. GOODLIN, Examiner. 

